Various industries have networks associated with them. One such industry is the utility industry that manages a power grid. The power grid may include one or all of the following: electricity generation, electric power transmission, and electricity distribution. Electricity may be generated using generating stations, such as a coal fire power plant, a nuclear power plant, etc. For efficiency purposes, the generated electrical power is stepped up to a very high voltage (such as, for example, 345K Volts) and transmitted over transmission lines. The transmission lines may transmit the power long distances, such as across state lines or across international boundaries, until it reaches its wholesale customer, which may be a company that owns the local distribution network. The transmission lines may terminate at a transmission substation, which may step down the very high voltage to an intermediate voltage (such as, for ex ample, 138K Volts). From a transmission substation, smaller transmission lines (such as, for example, sub-transmission lines) transmit the intermediate voltage to distribution substations. At the distribution substations, the intermediate voltage may be again stepped down to a “medium voltage” (such as, for example, from 4K Volts to 23K Volts). One or more feeder circuits may emanate from the distribution substations. For example, four to tens of feeder circuits may emanate from the distribution substation. The feeder circuit is a 3-phase circuit comprising 4 wires (three wires for each of the 3 phases and one wire for neutral). Feeder circuits may be routed either above ground (on poles) or underground. The voltage on the feeder circuits may be tapped off periodically using distribution transformers, which step down the voltage from “medium voltage” to the consumer voltage (such as, for example, 120V). The consumer voltage may then be used by the consumers.
To meet customers' demands on multi-type energy locally, distributed generation (DG) and smart grid has been developed. With their increasingly development, a micro grid (MG) is playing a more and more important role in DG penetration handling, utilization of renewable energy and emission mitigation. The MG could further provide both heating energy and cooling energy to the customers with higher energy utilization efficiency. Therefore, more and more MG projects are under planning and construction. In a power grid including the MG, the equipment utilization and device cost are highly dependent on device capacity determination. Therefore, it is very important to determine suitable capacity for the MG so that the equipment can be utilized efficiently and at the same time, the customer's energy demands can be met.
However, in the prior art, there is no such a capacity determination approach specifically for the MG Besides, capacity determination approaches for the traditional bulk power grid cannot be used for the MG because, quite different from the traditional bulk power grid, the MG includes multi-type energy source devices, which can supply a plurality of energies, such as the electricity, the heating energy and the cooling energy.
Thus, in the art, there is a need for an optimal capacity determination approach for the MG.